Block copolymer modified bitumens, and felts, coatings, sealants and roads made therefrom

ABSTRACT

The invention relates to thin block copolymer modified bituminous felts, comprising at least one block copolymer, comprising at least two poly(vinyl aromatic) blocks and at least one poly(conjugated diene) block, in a weight proportion of from more than 20 to 50 wt %, relative to the weight of the block copolymer and bitumen and optionally at least one filler, in a weight proportion in the range of from 0 to 50 wt %, relative to the weight of the complete composition and wherein the respective weight proportions of block copolymer, bitumen and filler add up to 100%. The invention also relates to the block copolymer modified bituminous composition, and the use thereof in bituminous pavements, coatings and sealants.

TECHNICAL FIELD

The present invention relates to block copolymer modified bitumens, tofelts, coatings, sealants and roads made from said block copolymermodified bitumens, and the use of said felts for roofing and forapplication in construction and/or building industry, e.g. bridge decklayers and protective layers for concrete, steel and/or otherconstructions.

More in particular the present invention relates to block copolymermodified bitumens which comprise a block copolymer of vinyl aromatic andconjugated diene and to felts made from them which can be of asignificant smaller thickness as compared to the conventional feltswithout affecting the felt's functional performance.

DESCRIPTION OF BACKGROUND ART

During the last two decades of the manufacture of block copolymermodified bituminous compositions, in particular for roofing, a cleartrend has developed which aimed at using one or more block copolymers inbitumen, in actual weight proportions of up to 15 wt %, relative to theweight of the bitumen and block copolymer, while fillers wereincorporated in actual weight proportions in the range of from 20 to 40wt %, relative to the weight of the complete composition.

Such bituminous compositions were known from e.g. U.S. Pat. Nos.4,405,680; 4,904,713; 5,051,457; 5,447,775; 5,308,676; 5,719,216;5,854,335; 5,798,401 and 6,120,913.

As said block copolymers clearly formed and still form the mostexpensive elements of such modified bituminous compositions, there wasno incentive at all for economical reasons to look for significantlyincreased proportions of such block copolymers.

On the other hand a clear economical need has developed to provideroofing felts and other protecting felts in the building industry, whichcan be applied as sole single felt, which should be able to form aadequate barrier against water e.g. rain water or ground water, whichmoreover can contain increasing amounts of corrosive agents (securingwater tightness) instead of the commonly applied multilayer systems, andwhich should not increase the weight of the complete construction and inparticular roofs.

It is therefore an object of the present invention to provide blockcopolymer modified bituminous compositions and felts derived from them,which meet the hereinbefore mentioned conditions.

Another object of the present invention is the use of such blockcopolymer modified bituminous felts in building and/or engineeringindustry in an economically improved way.

A further object of the present invention is the use of said improvedblock copolymer modified bituminous compositions in bituminouspavements. The structural elements of a typical bituminous pavementcomprises the pavement foundation (made of sub-grade, that is thenatural soil of fill material, and sub-base, usually formed of goodquality granular material); the road base, made of dense or openbituminous material, and the surfacing, comprising a base course and awearing course. The load-carrying capacity of a pavement is a functionof both the thickness of the material and its stiffness. The thicknessof the base course therefore depends on the use of the pavement. It mayvary from for instance 60 mm (cycle roads) to 180 mm and more (heavilyloaded roads). Replacing e.g. the bituminous composition used for thebase course of the surfacing by the composition of the presentinvention, provides, in a manner similar to the bituminous felts,economically improved base courses that are about 2/3^(rd) of theordinary thickness, whilst providing a well shaped surface on which toconstruct the wearing course as well as to distribute the traffic loadsover the road base.

SUMMARY OF THE INVENTION

As result of extensive research and experimentation, improved blockcopolymer bituminous compositions and felts and bituminous pavementsderived from them, have surprisingly been found.

Accordingly, the invention relates to copolymer modified bituminouscompositions, and felts as well as bituminous pavements derived fromthem, comprising at least one block copolymer, comprising at least twopoly(vinyl aromatic) blocks and at least one poly(conjugated diene)block in a weight proportion of more than 20 wt % and more particular inthe range of from more than 20 to 40 wt %, relative to the weight of theblock copolymer and bitumen, and optionally at least one filler, in aweight proportion in the range of from 0 to 50 wt %, relative to theweight of the complete composition, and wherein the respective weightproportions of block copolymer, bitumen and filler add up to 100%.

DETAILED DESCRIPTION OF THE INVENTION

The invention is hereafter discussed in respect of the use in bituminousfelts in particular, although it is to be understood that theimprovement may be found in bituminous pavements as well. The bituminouscompositions may also be used in bituminous sealants and coatings.

With the term “thin”, as used throughout the present specification, ismeant that the block copolymer modified bituminous felts or base coursesof the present invention can have a thickness which is in averagereduced by about 40% as compared to similar prior art bituminous feltsor pavement component, while the relevant mechanical properties havebeen significantly improved into an excellent package.

More in particular the service temperature of said bituminous felts ofthe present invention have been found to be increased from e.g. 110° C.to 170° C., the cold bend temperature has been found to be decreasedfrom −30° C. to −50° C. or lower, while a high stiffness(walk-on-ability) was found in combination with an excellent lowtemperature flexibility.

It will be appreciated that such properties allow a substantialreduction in felt thickness without affecting the felt's functionalperformance requirements, i.e. sealing surfaces and securing watertightness.

This results in lower weight felts and potential significant economicaladvantages.

Moreover, the high level of copolymer modification will strengthen theservice lifetime guarantee of critical performance indicators forprotection against outside water, and in particular roofingapplications.

It will be appreciated that the extra costs of the additional amounts ofblock copolymer in the bituminous compositions of the present inventionwill be much more than compensated by the surprisingly found advantagesof the package of improved properties and the enabled use ofsignificantly thinner felts.

As mentioned, similar advantages may be had when the composition is usedin bituminous pavements, in particular the base course thereof, wherereduction of thickness and increase in service temperature range issimilarly appreciated.

The vinyl aromatic monomer to be incorporated into the block copolymermay be selected from styrene; o-methyl styrene; p-methyl styrene;p-tert-butyl styrene; 2,4-dimethylstyrene; alpha-methyl-styrene; vinylnaphthalene; vinyl toluene and vinyl xylene or mixtures thereof. Apreferred vinyl aromatic monomer is styrene as substantially purehomomonomer or as main monomers, mixed with minor proportions (at most10 wt %) of one or more of the other structurally related vinyl aromaticmonomer(s) as specified hereinbefore, or with minor proportions of acomonomer (e.g. butadiene or isoprene). The use of substantially purestyrene is most preferred.

The conjugated diene monomer can be selected from butadiene; isoprene;2,3-dimethyl 1,3-butadiene; 1,3-pentadiene, 1,3-hexadiene and mixturesthereof. Preferred conjugated diene comonomers are butadiene or isopreneor mixtures thereof. Said mixtures of butadiene and isoprene can becopolymerized into a central block, comprising individual homopolymerblocks of poly(butadiene) and poly(isoprene) or one sole substantiallyrandom copolymerized block, having average homopolymer block lengths ofless than 100 monomer units and preferably of less than 20 monomerunits. A more preferred conjugated diene comonomer is butadiene, whichcan be used as substantially pure comonomer alone (content more than99%), or as main monomer, mixed with minor proportions (at most 10 wt %)of one or more of the hereinbefore specified structurally relatedconjugated diene monomer or with minor proportions of a vinyl aromaticcomonomer such as styrene. The use of a substantially pure butadiene ispreferred.

The block copolymers may be either linear or radial and will preferablyhave apparent total molecular weights in the range of from 40,000 to500,000 and more preferably from 60,000 to 200,000.

It will be appreciated that the main linear triblock copolymers orradial block copolymers may also comprise relatively minor amounts ofaccompanying diblock copolymers, comprising the same poly(vinylaromatic) block, and a poly(conjugated diene block) of an apparentmolecular weight, being the half of the molecular weight of the centralblock poly(conjugated diene block) in a triblock and resulting from themanufacture of said triblock copolymer or radial block copolymer bycoupling initially prepared living diblock copolymers with a couplingagent, as illustrated in e.g. U.S. Pat. Nos. 3,231,635; 3,251,905;3,390,207; 3,598,887 and 4,219,627 and EP patent applications nos.0413294A2; 0387671A1; 0636654A1 and WO 04/22931, the disclosures ofwhich have been incorporated herein by reference.

The diblock content can be in the range of from 0 to 90 wt % andpreferably from 0 to 35 wt %, and more preferably from 0 to 20 wt %,relative to the total weight of block copolymer(s).

The 1,2-addition during the polymerization of conjugated diene andpreferably butadiene (vinyl content) is generally in the range of from 5to 65 mole %, preferably in the range of from 8 to 45 and morepreferably from 8 to 25 mole %.

The block copolymers may have bound vinyl aromatic monomer contents inthe range of from 15 to 50 % and more preferably from 25 to 45 % andwill have a linear triblock structure or radial structure (S—B—S or(SB)_(n)—X). More preferred block copolymers are linear triblock (S—B—S)copolymers.

Examples of suitable block copolymers to be used according to thepresent invention are KRATON D1101, the road paving benchmark grade,KRATON D1102, a low molecular weight, linear block copolymer for a lowmelt viscosity, KRATON D 1116 A radial, low styrene block copolymer forblends with a higher butadiene requirement, KRATON D1118, a highdi-block containing granular polymer, also for use in combination withvulcanisation agents such as sulphur, KRATON D1186 and KRATON D1184,which are the main grades for roofing felts, KRATON D1192, a grade withlower PMB viscosity, high compatibility and good ageing performance,KRATON KX219 and KRATON KX220 block copolymers (KRATON is a registeredtrademark). In roofing felts also isoprene based styrenic blockcopolymers are used, to formulate self-adhesive felts. Block copolymersmay be had from suppliers such as Polimeri Europa; Dynasol; Dexco; Fina;Chi Mei; Asahi; Taiwan Synthetic Rubber Company; Kumho; LCY and Yue Yangand others, that supply grades similar to the aforementioned KRATONgrades.

It will be appreciated that the applied block copolymers may also havebeen selectively hydrogenated, which means that the poly(conjugateddiene) central block(s) may have been fully or partially hydrogenated(residual unsaturation less than 25% of the original unsaturation),whereas the poly(vinyl aromatic) blocks have not been hydrogenated, e.g.as known from U.S. Pat. Nos. 3,113,986; 4,226,952; 5,039,755 and Reissueno. 27145, the disclosures of which are herein incorporated byreference. The use of said hydrogenated block copolymers (S-EB—S or[S-EB]_(n)-X) will provide as additional advantageous feature, that noprotecting agent on the block copolymer modified bituminous felt uppersurface will be necessary, such as slate chippings and the like.Examples of said block copolymers are KRATON G1650, G1652 and G1654block copolymers. Other suppliers include Dynasol, Kuraray, Asahi, andTaiwan Synthetic Rubber Company.

In preferred block copolymer modified bituminous compositions of thepresent invention, the weight proportion of block copolymers will be inthe range of from more than 20 to 40 wt %, relative to the weight of thebitumen and block copolymer.

The bitumen can be selected from naturally occurring bitumens orbitumens derived from mineral oil. Also petroleum pitches obtained by acracking process and coal tar can be used as the bituminous component,as well as blends of various bituminous materials.

Examples of suitable components include distillation or “straight-runbitumens”. Precipitation bitumens, e.g. propane bitumens, blownbitumens, e.g. catalytically blown bitumen or “multiphalte”, andmixtures thereof.

Other suitable bituminous components include mixtures of one or more ofthese bitumens with extenders (fluxes) such as petroleum extracts, e.g.aromatic extracts, distillates or residues, or with oils.

Suitable bituminous components (e.g. either “straight-run bitumens” or“fluxed bitumens”) are those having a penetration in the range of from10 to 350 dmm at 25° C. (as measured according to ASTM D5, lower valuesindicate harder bitumen). In typical bituminous pavements, bitumenshaving a penetration in the range of from 40 to 150 dmm at 25° C. arepreferred. Depending on the climate and the intended use, in some basecourses bitumen with a penetration down to 10 dmm may be used. On theother hand, in typical roofing felts bitumens are preferred that have apenetration in the range of from 100 to 300 dmm at 25° C.

It is the advantage of the present invention that now bitumens may beused that would normally be considered too hard. Accordingly, preferablyquite hard bitumens of a penetration of from 10 to 100 dmm and morepreferably from 30 to 80 dmm may be used.

The block copolymer modified bituminous compositions of the presentinvention may also comprise other ingredients that may be required dueto the specific end-use envisaged.

Said other ingredients may be flame retarders, stabilizers,anti-statics, resins, oils, occurring in weight proportions in the rangeof from 0 to 15 wt %, relative to the weight of block copolymer andbitumen.

Fillers are included such as talc, calcium carbonate, carbon black flyash, slate dust, limestone, dolomite and siliceous fillers such as clay,mica and other sheet silicates or mixtures of said fillers. Inbituminous pavements, aggregate and sand is used.

The block copolymer modified bituminous compositions of the presentinvention may be prepared by various methods.

The block copolymer and bitumen can be blended at an elevatedtemperature, preferably not higher than 190° C. for unhydrogenated blockcopolymers and not higher than 230° C. for hydrogenated blockcopolymers, in conventional high shear blenders such as a ribbonblender, a drum mixer, where after the filler can be mixed in, whereinlower molecular weight block copolymers have been included.

For compositions wherein relatively higher molecular weight blockcopolymers have been included, blending of block copolymer with bitumenmay be carried out by calendaring, in a Branbury internal mixer or anyother means known to be used for blending high viscous compositions.

It will be appreciated that the block copolymer modified bituminousfelts of the present invention will have a thickness of from 1 to 5 mm;preferably from 1.5 to 2.5 mm for roofing felts and from 2.5 to 3.5 mmfor bridge deck layers.

Said modified bituminous felts may be applied as one single layer andare therefore significantly cheaper than conventional felts and/ormultilayer systems.

The block copolymer modified bituminous felts of the present inventionhave a service temperature of from −35° C. or lower.

The new bituminous pavements may have base courses of about 40 mmthickness, whilst maintaining the properties of an ordinary base courseof 60 mm thickness.

The following examples illustrate the present invention, however withoutrestricting its scope to these specific embodiments.

EXAMPLES

Several block copolymers and bitumen grades were mixed in a SILVERSONLR2 high shear mixer in weight proportions as specified in the followingtable. The bitumen was heated to 160° C. and subsequently the blockcopolymers were added. During polymer addition the temperature was keptunder 180° C. Blending was continued until a homogeneous blend wasobtained. A filler, if any, was added under mixing.

Conclusion

The block copolymer modified bitumen compositions of Examples I and III(vs. comparative Examples II and IV) exhibit an outstanding balancebetween high stiffness (low Pen at 50° C.) and excellent Low Temperatureperformance. This results in a superb Service Temperature range.Moreover, the novel compositions maintain their low Cold Bend propertyeven if use is made of (cheap) filler. Examples V and VI demonstratethat the invention is not limited to a specific block copolymer ofbitumen.

Although not demonstrated here, the new block copolymer modifiedbituminous compositions may be used in other end-uses as well Example IIII(a) III(b) V VI Comparative Example II IV(a) IV(b) Bitumen B45/60, %wt 75 88 75 Bitumen PX-60, % wt 75 75 88 88 Bitumen B-160, % wt 75Filler, % wt on total 35 35 Block copolymer A, % wt 25 12 25 25 12 12 25Block copolymer B, % wt 25 Properties of compositions Softening pointR&B, ° C. 140 112 139 139 110 111 112 145 Pen at 25° C., dmm 25 31 18 1832 23 21 32 Pen at 50° C., dmm 48 96 44 44 104 87 50 63 Cold Bend, pass° C. −50 −15 −50 −50 −30 −25 −50 −50 DIN Flow, pass ° C. 120 90 120 12085 85 90 135 Service temperature range, ° C. 170 105 170 170 125 120 140185

The test methods used were:

Viscosity: evaluated at 180° C. using a Haeke roto-viscosimeter, using ashear rate of 20 s⁻¹ and 100 s⁻¹

Cold blend: according to UEAtc M.O.A.T. no. 31; 1984,

Flow Resistance Temperature: according to DIN 52123; August 1985,

Softening point R&B: according to ASTM D36, corrected for stirring with+1.5° C.,

Penetration: at 25° C. or 50° C. according to ASTM D5-94.

The bitumen grades used for the listed examples were compatiblebitumens:

PX-60 bitumen is a mixture of 81 wt % of propane bitumen ex-Phillipines(Pililla, TMC no. 26260)+19 wt % of Bright Furfural Extract (BFE,aromatic oil/flux, TMC no. 24206), showing a penetration of 60 dmm at25° C.

B45/60 is a bitumen obtained by vacuum distillation of Venezuelan crudeoil (in ESHA refinery, Amsterdam), having a penetration of 50 dmm at 25°C.

B-160 is a bitumen obtained by vacuum distillation of Middle East crudeoil supplied by SIPLAST (TOTAL), showing a penetration of 160 dmm at 25°C.

Block copolymer A is a triblock copolymer, comprising poly(styrene)blocks and a poly(butadiene) block, having a PSC of 31 wt %, a totalmolecular weight of 171,000, a vinyl content of 8 mole % and a couplingefficiency of 80%.

Block copolymer B is a triblock copolymer, comprising. poly(styrene)blocks and a poly(butadiene) block, having a PSC of 29.5 wt %, a totalmolecular weight of 127,000 (measured by Gel Permeation Chromatographyand expressed in terms of standard poly(styrene)), a coupling efficiencyof 84% and a vinyl content of 8 mole %.

As filler was used either WIGRO 60K or Betocarb P2 limestone (WIGRO andBetocarb are trademarks).

1-10. (canceled)
 11. A thin block copolymer modified bituminous feltcomprising at least one block copolymer, which comprises at least twopoly(vinyl aromatic) blocks and at least one poly(conjugated diene)block in a weight proportion of from more than 20 to 50 wt % relative tothe weight of the block copolymer, and bitumen and optionally at leastone filler in a weight proportion from 0 to 50 wt % relative to theweight of the complete composition and wherein the respective weightproportions of block copolymer, bitumen and filler add up to 100%. 12.The thin block copolymer modified bituminous felt according to claim 1wherein the weight proportion of block copolymer is from more than 20 to40 wt % relative to the weight of the block copolymer and bitumen. 13.The thin block copolymer modified bituminous felt according to claim 1having a service temperature from 140 to 200° C. and a cold bendtemperature of −35° C. or lower.
 14. The thin block copolymer modifiedbituminous felt according to claim 1 wherein the conjugated diene is1,3-butadiene, isoprene or a mixture of 1,3-butadiene and isoprene. 15.The thin block copolymer modified bituminous felt according to claim 1wherein the block copolymer is a linear triblock copolymer S—B—S or acoupled radial block copolymer (S—B)_(n)—X, optionally mixed withdiblock S—B, wherein each S independently represents poly(styrene) andeach B independently represents poly(butadiene) and wherein the diblockcopolymer occurs in a weight proportion from 0 to 35 wt %.
 16. The thinblock copolymer modified bituminous felt according to claim 1 whereinthe block copolymer is selectively hydrogenated and is a linear triblockcopolymer S-EB—S or a coupled radial block copolymer (S-EB)_(n)—X,optionally mixed with diblock S-EB, wherein each S independentlyrepresents poly(styrene) and each EB independently representshydrogenated poly(butadiene) and wherein the diblock copolymer occurs ina weight proportion from 0 to 35 wt %.
 17. The thin block copolymermodified bituminous felt according to claim 1 wherein the boundpoly(vinyl aromatic) content in the block copolymer is from 25 to 45 wt%.
 18. The thin block copolymer modified bituminous felt according toclaim 1 wherein the 1,2-addition in the conjugated diene polymerizationis from 5 to 65 mole %.
 19. The thin block copolymer modified bituminousfelt according to claim 1 wherein the apparent total molecular weight ofthe block copolymer is from 40,000 to 500,000.
 20. The thin blockcopolymer modified bituminous felt according to claim 1 having athickness from 1 to 5 mm.
 21. The thin block copolymer modifiedbituminous felt according to claim 20 wherein the bituminous felt is aroofing felt having a thickness from 1.5 to 2.5 mm.
 22. The thin blockcopolymer modified bituminous felt according to claim 20 wherein thebituminous felt is a bridge decking layer having a thickness from 2.5 to3.5 mm.
 23. The thin block copolymer modified bituminous felt accordingto claim 1 wherein the bituminous felt consists of a single layer.
 24. Athin block copolymer modified bituminous pavement comprising at leastone block copolymer, which comprises at least two poly(vinyl aromatic)blocks and at least one poly(conjugated diene) block, in a weightproportion from more than 20 to 50 wt % relative to the weight of theblock copolymer and bitumen, and optionally at least one filler in aweight proportion from 0 to 50 wt % relative to the weight of thecomplete composition, and wherein the respective weight proportions ofblock copolymer, bitumen and filler add up to 100%.
 25. The thin blockcopolymer modified bituminous pavement according to claim 24 having abase course thickness of about 40 mm.
 26. A block copolymer modifiedbituminous composition wherein the bitumen has a penetration value at25° C. (according to ASTM D5) from 10 to 350 dmm, and wherein the blockcopolymer occurs in a weight proportion from more than 20 to 50 wt %relative to the weight of bitumen and block copolymer.
 27. The blockcopolymer modified bituminous composition according to claim 26 whereinthe block copolymer is a linear triblock copolymer S—B—S or a coupledradial block copolymer (S—B)_(n)—X, optionally mixed with diblock S—B,wherein each S independently represents poly(styrene) and each Bindependently represents poly(butadiene) and wherein the diblockcopolymer occurs in a weight proportion from 0 to 35 wt %.
 28. The blockcopolymer modified bituminous composition according to claim 26 whereinthe bound poly(vinyl aromatic) content in the block copolymer is from 25to 45 wt %.
 29. The block copolymer modified bituminous compositionaccording to claim 26 wherein the 1,2-addition in the conjugated dienepolymerization is from 5 to 65 mole %.
 30. The block copolymer modifiedbituminous composition according to claim 26 wherein the apparent totalmolecular weight of the block copolymer is from 40,000 to 500,000.